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Proper fuel pressure  

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  1. 1. Proper fuel pressure

    • Below 10 psi
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    • Above 10 psi


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Ok gang! Going to make this as simple as possible. On another forum everyone is now believing that 5 psi is a good fuel pressure to run. This is being said by a supplier that sells VP pumps. Although the Dodge service manual says 10 psi is the minimum. I have recently had correspondence with Cummins on this topic and they say "10 psi is the minimum" for the engine. I want you all to know I run 17 psi and am HAPPY with this pressure. What do you feel is the proper pressure to run?

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I'm a newb to this stuff but from what I have gathered above 10 is good. With my stock pump and filter my pressure was at around 12 at idle and dropped to less than 10 under a good load. I feel more comfortable with my new setup. Idle at above 15 and about 14 under load.

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Yeah ISX is cheating and pulling my photoshop pic...:lmao: But I agree I would keep it in the green... :thumbsup:

What do you expect, you keep playing with things, giving me all this time to take credit for your work :lol3: You would think all pictures from that part of the site would bear the Mopar1973Man logo at the bottom, like all my album pictures :lmao2:

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Ok gang! Going to make this as simple as possible. On another forum everyone is now believing that 5 psi is a good fuel pressure to run. This is being said by a supplier that sells VP pumps. Although the Dodge service manual says 10 psi is the minimum. I have recently had correspondence with Cummins on this topic and they say "10 psi is the minimum" for the engine. I want you all to know I run 17 psi and am HAPPY with this pressure. What do you feel is the proper pressure to run?

Is that the Northeastern supplier by any chance?

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I have recently had correspondence with Cummins on this topic and they say "10 psi is the minimum" for the engine. I want you all to know I run 17 psi and am HAPPY with this pressure. What do you feel is the proper pressure to run?

Kind of funny Cummins wants you to have 10+ PSI, and then they supply the engine with a POS pump?

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I'll bet they had a good one on it and dodge told them their mechanics needed something to work on so they put that one on it instead :lol3: Just like the silencer ring and various emissions things....

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Kind of funny Cummins wants you to have 10+ PSI, and then the supply the engine with a POS pump?

Actually it like all thing on the market Cummins and Dodge both bid for manufacture that are the cheapest to supply part and Federal Mogul (Carter) happen to be the lowest bid at the time. They most like test drove the truck for a short time and was happy with it and then it hit the market... Like a lot of people are quoting Blue Chip for 5 PSI is more than enough fuel for the VP44... Yeah sure that when you take a new pump put in on the test stand for a few hours and disassemble the pump. Nope no wear must be ok... Now try that on a VP44 mounted in a truck and put it through its paces for 700K to 1 million miles I doubt it will barely make 50K miles and puke like mine did...

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I am going to have to disagree with the poll and the premise of the question it poses. 10 psi, is the ragged, rock bottom, unsatisfactory minimum to get by. The VP-44 can fuction adequate with this inadequate fuel pressure the the fuel return valve is not going to open allowing any excess fuel to return to the tank and thus aid in the absolutely essential task of cooling the VP-44. In my opinion, 15 psi is the minimum adequate fuel pressure. This not only provides full fuel for engine operation but also provides adequate cooling and lubrication of the injector pump.

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I am going to have to disagree with the poll and the premise of the question it poses. 10 psi, is the ragged, rock bottom, unsatisfactory minimum to get by. The VP-44 can fuction adequate with this inadequate fuel pressure the the fuel return valve is not going to open allowing any excess fuel to return to the tank and thus aid in the absolutely essential task of cooling the VP-44. In my opinion, 15 psi is the minimum adequate fuel pressure. This not only provides full fuel for engine operation but also provides adequate cooling and lubrication of the injector pump.

Very well put... But is true... 15 PSI will crakc open the overflow valve and allow the fuel to flow on the return side and aid in cooling...

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I am going to have to disagree with the poll and the premise of the question it poses. 10 psi, is the ragged, rock bottom, unsatisfactory minimum to get by. The VP-44 can fuction adequate with this inadequate fuel pressure the the fuel return valve is not going to open allowing any excess fuel to return to the tank and thus aid in the absolutely essential task of cooling the VP-44. In my opinion, 15 psi is the minimum adequate fuel pressure. This not only provides full fuel for engine operation but also provides adequate cooling and lubrication of the injector pump.

Everything you say I would have to agree on. I could have worded it differently. My whole point of writing the post was that someone else other than the manufacturer of the engine was saying that Cummins was wrong and that the correct pressure was lower than what was recommended. I believe everyone on this forum is running above 15 and below 20 psi because they understand the operation of the pump and when the return valve opens. Thanks for clarification on my post! It would be like me saying that Mike is wrong in the way he "counts what is a post on his forum!"

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It would be like me saying that Mike is wrong in the way he "counts what is a post on his forum!"

Just got to pick on me don't you...:lmao2: But...

I believe everyone on this forum is running above 15 and below 20 psi because they understand the operation of the pump and when the return valve opens.

I feel the same way I rather crack open the overflow valve slightly and have just a bit more pressure feeding the pump without being excessive.

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Like I posted before 17k and on my 4th vp44. If it wasnt a cummins I would have trashed this truck a long time ago. I think I round trip my last one in 3 hours.

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Question: The guy up in the northeast that sells the rebuilt vp44's and is saying that you have adequate needs with 5p.s.i., how long is the warranty on his rebuilt pumps? I guess I am wondering why he would say 5 p.s.i. is sufficent, if he is going to warranty his vp44's, after telling us that 5 p.s.i. is enough. Or, am I missing something here ? Seriously, not trying to be sarcastic.

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In the same breathe he says "5 PSI is enough", but Bosch turns around and says " That diaphram damage is caused from low fuel pressure". Then your 5 PSI buddy mentions that if there is a "diaphram rupture" no one will warranty the pump!So is it worth the risk? (Personally No.)Has our 5 PSI buddy done any long testing of this? 100K, 200K, or 500K miles? (None documented as of yet!)

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this is off http://www.bluechipdiesel.com/fassinfo.html i bolded what i thought is important

Blue Chip Diesel Performance proved in 1999 that 5 PSI, under load, made all the horsepower the VP44 pump could make, even with stock fuel lines, fittings and supply pump. We did this test on a dyno when we were testing our Fuel Management System. We thought the amount of return fuel flow at this pressure was adequate for internal lubrication. This proved to be all good information as it turned out, just not enough information. We didn’t know then what we do now, namely that of the heat issue, so we never measured the temperature of the return fuel under a variety of operating conditions.

and earlier:

This is from listening to all of you in the “Real World” and testing the accuracy of my diagnostic procedures daily. I am convinced that HEAT IS THE KILLLER OF THESE PUMPS, based on information I have learned over the years. I got this information by listening to all the great people who call me for technical help, and keeping track of initial as well as repeat failures.

ohh...notice he doesn't say what load %? i mean exhaust brake and 3 cylinder idle = 33% load. mind you at idle!

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this is off http://www.bluechipdiesel.com/fassinfo.html i bolded what i thought is important

Blue Chip Diesel Performance proved in 1999 that 5 PSI, under load, made all the horsepower the VP44 pump could make, even with stock fuel lines, fittings and supply pump. We did this test on a dyno when we were testing our Fuel Management System. We thought the amount of return fuel flow at this pressure was adequate for internal lubrication. This proved to be all good information as it turned out, just not enough information. We didn’t know then what we do now, namely that of the heat issue, so we never measured the temperature of the return fuel under a variety of operating conditions.

Ah Ha... Here is the kicker... There is no return from the VP44 if the pressure is at 5 PSI... The overflow valve doesn't open till 14 PSi... So how can there be return fuel??? Also never mention the suppling pumps GPH rating??? (Stock, AD 100, FASS 95??) Another thing how long was it on the dyno 2-3 minutes? 1 hour? 10 miles?

and earlier:

This is from listening to all of you in the “Real World” and testing the accuracy of my diagnostic procedures daily. I am convinced that HEAT IS THE KILLLER OF THESE PUMPS, based on information I have learned over the years. I got this information by listening to all the great people who call me for technical help, and keeping track of initial as well as repeat failures.

As for heat failures then you would see more pumps failing in the south and not the north... Fairly common even up here in Idaho to see VP44 fail... I don't think its all about heat though... I might be a factor but not the main one... Maybe the heat factor is from the fact the overflow is completely closed and there is NO extra fuel for cooling and the return fuel is coming from the injectors bleeding off.

ohh...notice he doesn't say what load %? i mean exhaust brake and 3 cylinder idle = 33% load. mind you at idle!

I added my tidbit again... Because as for BC post is rather general and doesn't give important information... The only number he gives is the 5 PSI number... So what I can place my truck on a dyno and product max power at 5 PSI... But there is nothing said about max lifespan... Remember if he told the truth about that then he'd be out of a job... :wow:

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Not to defend him or nothing, but he does recommend the Fass DDRP for longer life. Sure the VP44 will run with no lift pump pressure at all, my original VP44 did it a bunch of times, and I did not know it, till I got hesitation, or I could not prime the fuel filter, but that does not make it good. Maybe I should send him a link to this site and let him read this thread, that is bad information to tell your customers, he could at least put a disclaimer?WARNING, DO NOT DO THIS TO YOU VP44, THIS WAS ONLY A TEST, IT WILL VOID YOUR WARRANTY!!!!!Actually, they did that back in 1999 when the VP44 was in its infancy, but it should still not be presented on his web page, I agree.

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Not to defend him or nothing, but he does recommend the Fass DDRP for longer life.

Look at it this way: stock pump, auto store pumps, DDRP, mechanical pump, FASS-AirDog-Raptor pumps. The further away from stock pump the longer it will last plus the better service you will get out of the VP. I suppose you could also add the particulates in the fuel into the mix as well. The more particulates and a poor fuel filter will mess up both pumps as well!

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i wasn't trying to bad mouth anyone. but that info is on that site. you paid for that pump...i'm not the one going to tell you what you can and cannot do with your property, but even wise Cummins said 10psi minimum at any load! i personally believe that you need to have fuel "carry" the heat away. its like the cpu in your computer. it might boot up for a couple of seconds with no heatsink...but in a minute you will know what burnt silcone and copper smells like! run a VP44 with minimum cooling....your going to know what a empty wallet feels/smells like!

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Little rough around the edge but... The point is valid...

We all know the Vp44 injection pump runs without a lift pump. How many times do we tell people to install a fuel pressure gauge to find out they report 5 PSI down to 0 PSI. This far to common to see... Typically the owner changes the lift pump quickly with another stock pump hoping to fix it. But typically the pump starts spitting codes out like P0216 and others...

The point here is at what pressure do you get the most life from a VP44?

None of use are worried about the minimum pressure that creates MAX horsepower... Very few of us here even go out racing. But is the whole Blue Chip article there is nothing said about maximum lifespan, testing in regards to lifespan, extended dyno testing for lifespan. Just nothing...

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Little rough around the edge but... The point is valid...

We all know the Vp44 injection pump runs without a lift pump. How many times do we tell people to install a fuel pressure gauge to find out they report 5 PSI down to 0 PSI. This far to common to see... Typically the owner changes the lift pump quickly with another stock pump hoping to fix it. But typically the pump starts spitting codes out like P0216 and others...

The point here is at what pressure do you get the most life from a VP44?

None of use are worried about the minimum pressure that creates MAX horsepower... Very few of us here even go out racing. But is the whole Blue Chip article there is nothing said about maximum lifespan, testing in regards to lifespan, extended dyno testing for lifespan. Just nothing...

Mopar Man, Your question: "THE POINT HERE IS AT WHAT PRESSURE DO YOU GET THE MOST LIFE FROM A VP44?" and the ultimate correct answer should ( I believe ) be the GOLD STANDARD for this subject. In my opinion, your question could not be worded any better than that.Posted Image

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Thanks... That's what I'm after really... I've been through all the forum like CF.com and other and been beat down with all the race nuts quoting that line out of Blue Chips site... But what I realized there is 2 class of truck owners... 1. High performance / Racing/ Dyno Queen / Sled Puller2. Daily driver & Grocery getter.I found that there is way to much hype for the performance crowd and very little out there for the common Joe that drives to work and back home every day. Might drag a trailer on the weekends but basically the truck is light duty. Like myself my truck see a bit more than light duty and I skid logs, haul firewood, tow trailers full of firewood, etc. So getting back to the the BC comment is that has there been any kind of testing in this type of driving? (I can bet not!)So I think what we need to do is keep track of the fuel additives, fuel pump (names), fuel pressure, and lifespan of the VP44 and I bet you find there is a different amount of failure compared to the performance site are saying... :whistle:I know ol' JL Welding would jump on this signing the blues...:rolleyes:Another good question...."How do you get the most out of your VP44 lifespan?"

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